8RDA+/TwinMOS PC-3200 = Can't get past 185Mhz fsb! Help!

Since the chip is unlocked and at low mults to keep the CPU as near as possible to its rated speed, I'm trying to see how high the mem can go w/o a CPU overlock- so temps are not an issue.

185Mhz FSB/Mem - No problems.
190Mhz FSB/Mem - Crashes, or BSOD upon booting into XP.

I can do 2.6v mem (default) @ 185Mhz no problems, and to boot @ 190Mhz. Upping the mem voltage to 2.77v did not help. Does my RAM need more voltage?

190Mhz also causes file corruption, as reported from scandisk.

Specs:

XP1700+ T-Bred A
Epox 8RDA+ (Rev. 1.1)
2x 256MB TwinMOS PC-3200 (Winbond BH5)
ATI Radeon 9700 Pro 128MB
Seagate 80GB Barracuda IV

What is your memory timing in the bios?

have you considered to try the vdd mod?

i suggest upping the vcore on the cpu. your ram should reach 200 fsb without using 2.77V on it, since its rated PC3200. So i would look into checking if your giving the cpu enough volts when raising the ram to 190fsb.

Can you do me a favor and try setting the FSB to 166 and the Memory to 200 and see if it works?

My own system will not go above 180 FSB/Memory but will do 166/200 and 200/100. If yours is the same it makes me wonder if there’s some kind of incompatibility with the EP-8RDA+ and Twinmos/Winbond memory.

Set my FSB to 166 and mem to 200Mhz, and whattaya know, boots into XP no problems, passes a few Sandra Memory benches no problem (on my 8K5A3+ the Sandra Memory benchmark always caused the machine to randomly restart if the memory wasn't 100% stable).

Running the memory @ Turbo, 2.6v. No problems so far- except for the fact that performance is MUCH lower than with the FSB and Memory @ 185Mhz.

mine will run at 200mhz just not at 200mhz fsb . it's prolly because of the vd voltage

Next thing to try is setting the FSB at 200 and the memory at 50%. If it still works then your in the same boat as me. Both the FSB and memory bus work at 200Mhz just not at the same time. Next question would be why? Answer that and I would be a happy camper.

it might be your VDD is low.... you may want to consider to do a VDD mod.

Tried 200Mhz fsb/100Mhz memory, and it's 100% stable.

In the BIOS the VDD reads 1.56v- that what its supposed to be?

1.56v is default.. but many people tried to mod their vdd to 1.80v~ 2.00v to get 220mhz FSB SYNC~ 240mhz SYNC

That’s the thing though, where not trying to get 220 SYNC, we would be happy with 190. The thing is if we can do 200 FSB with memory at 50% shouldn't it be possible at 100% without the vvd Mod?

Here’s an idea. Try setting your fsb 20Mhz above the highest SYNC you can go and your memory to 50% and see what happens. I’d guess it would be too much fsb for your motherboard and your system wont boot. At least in my case though I’ve set my fsb 35Mhz (215Mhz) above my max stable SYNC setting (180Mhz) with no stability problems.

I’ve got two ideas I would like to try to see it this is a problem with the board or if it’s a vvd issue. One is obviously to try the vvd mod and see it you can get anymore SYNC speed out of it. Unfortunately my motherboard stopped working this last weekend so I’ve got nothing to try it on. The other is to see if others are having this problem while using Twinmos/winbond memory. Fortunately I do have two more EP-8RDA+ boards coming since the wife wanted a new computer, so I’ll see if I can replicate the problem with multiple boards.

Honestly I’m hoping it’s a compatibility problem so we can get some super Bios update that makes all are problems go away.

you might try some active coolling on the chipset.i added artic silver to mine and was able to gain a few mhz,went from 185 to 188 stable.next i'm getting another cooller for both the north and south bridges.

Wackygore,

I have the exact same board and same problem as you, except I use a stick of 512mb Corsair XMS3200 C2.5.

My 2100+ revB 0250 chip can do 13.5x166 (2.25) stable @ 1.725v, 40C load

I can do 13.5x166FSB, with 200mhz mem settings stable (even with aggressive timing and CL2)

I can do 11x 200FSB, but only with 75% mem (or 150mhz) stable,

BUT, when I tried to do increase to 200FSB/166MEM or 200FSB/200MEM, my computer won't post and give a ram error beep. After restarting, I go back down to 75%, loads to windows, everything perfect/stable.

Why can't we do 200FSB/200MEM? I used the most relaxed memory setting and running at CL2.5, but no luck? VDDR up to 2.9, no luck. How would the VDD help if it seems like a memory problem (the chipset doesn't seem to have problem running at 200FSB).

any ideas?

VDD: Voltage to the Chipset (North Bridge)

NForce2 chipset is very different from VIA Chipset. NForce 2 SPP is clock generator which sets 200mhz FSB to the memory bus.

I have the exact problem!!! I can run the memory at 200 or the fsb at 200 but not both together. I can run the memory at 160 an the fsb at 200 but 166 and 200 is a no go. I am starting to think the chipset needs more voltage for some reason.

Yep I think it is a voltage problem also. I am running my 8rda at 220Mhz FSB but ... and a big but..... I can only do it with my mem at 50%

Now if I run them in sync I can only achieve 187 FSB stable. I am using two sticks of Cosair 3500. My old 8rda with same chip and mem would run at 200 sync so it isn't the memory. Also I noted I don't have my power LED working with this MB but my old 8rda worked fine with the same LED. Something is wrong here. I also have the NB and SB cooled and the NB is an A3. Someone enlighten me here.

One thing you can try is using different dimm slots. Try booting with a high fsb with 1 stick in dimm2 at first, then move on to different slots. Try both sticks by themselves to see if it is a ram issue. See if that allows you to get any higher. Then move onto trying 2 sticks, in dual channel or single channel mode.

I can run 200fsb sync'd and stable in dimm2 and dimm3(1 stick or 2 stick single channel) but not if I have a stick in dimm1 at all. Having any ram in dimm1 only allows me to run at 196fsb. I have corsair pc3200c2.

-D

Thanks for the reply. But why would these boards be doing this? That doesn't make any sense how you can do 200 sync buy not dual mode?

Seperate memory controllers, and the trace lengths to the dimm slot( from cpu) are longer also( to dimm 1), longer traces SEEM to have more trouble.

Hm - I'll have to check this out. I am at 200/200 but that's it just like hitting a wall.

First off make sure yiou remove the NB cooler and apply AS instead of the gunk that they are using. Also a 40mm fan may be a good idea.

Secondly - my impression so far is that there may in fact be a voltage related bottleneck. Possibly try running your processor at 8.5x200 but at 1.4V. That may offer up more juice for the memory.

Yo